JEE Main 2019 — Solutions Question with Solution

Freezing point depression refers to the lowering of the freezing point of solvent upon the addition of solute. Boiling point elevation refers to the increase in the boiling point of a solvent upon the addition of a solute.

$∆{\mathrm{T}}_{\mathrm{b}}={\mathrm{iK}}_{\mathrm{b}}\mathrm{m}\Rightarrow 2={\mathrm{iK}}_{\mathrm{b}}\times 1............\left(\mathrm{i}\right)$

$∆{\mathrm{T}}_{\mathrm{f}}={\mathrm{iK}}_{\mathrm{f}}\mathrm{m}\Rightarrow 2={\mathrm{iK}}_{\mathrm{f}}\times 2...............\left(\mathrm{ii}\right)$

Dividing $\left(\frac{\mathrm{i}}{\mathrm{ii}}\right)$,

$1=\frac{{\mathrm{K}}_{\mathrm{b}}}{2{\mathrm{K}}_{\mathrm{f}}}$

${\mathrm{K}}_{\mathrm{b}}=2\mathrm{ }{\mathrm{K}}_{\mathrm{f}}$